Question

Earth taken out on digging a circular tank of diameter 14 metre is spread All Around The Tank uniformly to a width of 3.5 m to form and embankment of height 2 metre calculate the depth of circular tank

Answer 1

Radius of circular tank = 1/2 × 14 = 7m

let the depth of the tank be x metre

volume of earyh dug = πr²x = 22/7×7×7×x

= 154x m³

Internal radius of the embankment = radius of the tank

External radius of the embankment = ( 7 + 3.5) = 10.5

= Area of embankment =

22/7 [(10.5)² - 7²]

=

$\frac{22}{7} \times (10.5 + 7)(10.5 - 7) \\ \\ = \geqslant 192 . 5 {m}^{2} \\ \\ = \geqslant volume \: of \: embankment \\ \\ = \geqslant area \: \times height \\ \\ \geqslant 192.5 \times 2 = 385 {m}^{3} \\ \\ = \geqslant volume \: of \: embankment \: = volume \: \\ of \: earth \: dug \\ \\ = \geqslant 154x = 385 \\ \\ = \geqslant x = \frac{385}{154} \\ \\ = \geqslant 2.5m$

Answer 2

Refer to the above attachment